Apparatus for making double walled tube



E. F. SVEC APPARATUS FOR MAKING DOUBLE WALLED TUBE Original Filed Dec.16, 1957 Il lIIIIIIIIIfIIIlIIII/Ill l,

July 20, 1965 United States Patent 3,195,3.8d APPARATUS FR MAKNG DQUBELEWALLED 'EURE Emil Francis Svec, New Yaris, NE.; Viera li/i. Svcs,errecutris: ot said Emil Svcs, deceased, assigner to Flexigrip, luc.,New York, NX., a corporation of New York @riginal appiication Esc. 16,w57, Ser. No. 703,033, now Patent No. 3,683,495, dated May 7, i953.Divided and this application Apr. 30, i962, Ser. No. 196,025'

2 Ciairns. (Ci. itl-i4) This application is a division of U.S.application Serial No. 703,033, led December 16, 1957, now Patent No.3,088,495.

This invention relates to apparatus for making a multi- Walledthermoplastic strip` More specically, this invention relates toapparatus for making a multi-walled thermo-plastic strip includingfastener structure disposed along opposite edges of the strip forlocking the edges together and forming the strip into a tube.

According to certain important aspects of the present invention, thereis provided a thermo-plastic tube type strip having interlocking edgeswith a multi-Wall structure having a plurality of compartments whichdouble Walled strip has a number of advantages a few of which are nowdescribed. The double Wall tube construction provides increasedprotection for 4article or articles covered therein against mechanicaldamage, and against dirt, voil and the like. This double wall stripstructure also has high insulating properties. Double Walled tubes ofthe present type also may be utilized to protectively enoase a series ofelectrical wires and the like.

Accordingly, it is an important object of the present invention toprovide apparatus for making a thermoplastic multi-walled stripconstruction having interlockingly engageable edges for folding thestrip into a tube.

A further object of the present invention relates to novel apparatus formanufacturing a multi-walled thermoplastic strip.

Yet another object of the present invention concerns a novel apparatusfor manufacturing a multi-Walled therrno-plastic strip having peripheraledges adapted for interlocked engagement to form the strip into a tube.

Yet another and still further object of this invention is to providemeans for extruding a multi-walled thermoplastic strip including meansfor maintaining the walls of the strip separated until they .arehardened so they will not collapse upon being discharged from theextruder.

Other and further important objects of this invention will becomeapparent from the following detailed description and the appendedclaims, and from the accompanying drawings illustrating a preferredembodiment of this invention, in which like reference numerals refer tolike parts and in which:

FIGURE l is a fragmentary, partly cross-sectioned extruder device shownextruding a strip, according to the features of the present invention;

FIGURE 2 is an enlarged fragmentary cross-sectional view takensubstantially on the broken section line iI-ll of FIGURE l, looking inthe direction indicated by the arrows;

FIGURE 3 is a fragmentary perspective view of a multi-Walledthermo-plastic strip provided with interlocking edges, according tocertain features of the present invention; and

FIGURE 4 is an enlarged fragmentary end elevation of the interlockededges of the double-walled tube shown in FIGURE 3.

The reference numeral l@ in FIGURE l indicates generally an extrudeddouble-walled strip and the reference numeral 11 in FIGURE 3 indicatesgenerally the strip 10 folded into tubular form in a manner which willhereiniili Patented July 20, i965 "ice after become apparent. In theform in which the strip lil would. be sold, it may be a flat strip ofextended length, capable of being bent transversely into the tube 11, orbeing wrapped about smaller tubes, cables or the like into the seamedtube-form shown in FIGURE 3.

The str-ip Iii is preferably -a strip of relatively thin, flexiblematerial, suitably formed from a plastic such as vinyl polymer orcopolymer, as for instance, polyvinyl chloride, or from polyethylene, orother susbtantially waterand moisture-proof plastic material having highdielectric strength and suitable strength against being torn or ruptureddespite its relative thinness..

According to the present invention, the strip is preferably extrudedfiat in a manner which will hereinafter be described in detail althoughit will be appreciated that the tube could be extruded initially intubular form, with the tube then being severed between the thickenededge portions to permit the tube to be flattened out.

As best shown in FIGURE 4, the thickened edge portions il and i3 areidentical in cross section but oi'set in opposite directions from theplane of the strip 10 and are adapte-d to confront each other whenoverlapped and formed into a tube. Since the closure strips 12 and 13are otherwise identical, only one need be described. A closure strip isprovided with alternating, adjacent grooves l5, 15a and ribs to, and idathat extend continuously along the edge portion i2. Two such grooves 15,15a and two such ribs lo, 16a are shown, although a greater number ofgrooves and ribs can be used if desired. The ribs and grooves arecomplementally formed and the ribs are provided with enlarged headportions 17 and restricted neck portions 1S, between which are formededges i9 that impart to the ribs a hook-like contour. When the closurestrips i2 and lf3 are matingly inter-engaged, the edges 1E of the ribslo, ida are in opposed relationship to resist lateral separation of theedges 12 and 13.

Closure of the tube to form the seam S can be effectuated manually byincrementally pressing together successive portions of the confrontingclosure elements of the edge portions l2 and i3. While a slider can beused for the purpose, it is preferable to take the slider away, once theclosure elements are engaged, since then the seam S will besubstantially Waterand moisture-tight throughout its extent. Where thearticle 10 is made of thermoplastic material, the seam S can bepermanently closed by cementing (gluing) the edges strips 12 and 13together along their contacting surfaces.

According to other important features of the present invention, thestrip l0 and the tube lll are provided with a multi-walled constructionwhich is here illustrated as a double walled form of my invention sinceadditional walls may be readily formed without departing from thisinvention. The double wall construction includes a iirst Wall 2@ whichWall has at its opposite ends the closure strips l2 and I3. A secondwall 2l is also mounted on the strip lo and tube il whereby link orhinge portions .Z2-22 are disposed at opposite ends of the Wall 21 andextend transversely with respect to the Walls 220 and 2l andinterconnect these walls generally at the area of the closure strips I2and i3. This double walled strip construction when utilized as a tubeprovides increased protection for articles covered therein againstmechanical damage, and against dirt, oil and the like. This double wallstrip structure also has high insulating properties. As will be notedfrom FIGURE 2, the rst wall 20 lies in a rst plane when the multiplewalled strip is lying fiat, and the edge closure strips 12 and 13 liealong the edges of the wall 20.

The second wall 21 is substantially parallel to the iirst wall 2d, andthe hinge portions 22 support it in a second plane. This structure alsomakes it more easy to form adsense Vthe multi-walled unit into a tube.it will be apparent `that the circumferences of the two layers must bedifierent, and to accommodate this change when the multiwalled strip isrolled into a tube, the hinge Vportions 22, 22 will bend, permitting thewalls to form a circle with- 'out undue stress. This also permits thetube to be rolled vin either direction, and in FIGURE 3 the tube isshown rolled with `the second wall 21 on the inside of the first wall20. As will be observed, the tube could be rolled in the other directionwith the second wall 2l on the outside. This Vcould easily beaccommodated in view of the laterally extending hinge portions 22, 22.Any pulling on the second wall portion 2l in the arrangement shown inFIGURE 3 will not result in a direct tensile stress being placed on thefirst wall 20, since the laterally extending hinge portions 22, 22 canfirst bend before directV pull is exerted on the first'wall 2t). lt willbe noted that the laterally extending hinge portions 22 position thesecond wall2l with a space between itrand the iirst wall 20. However, ifmaterial, such as a bundle of wires, is wrapped which have excesscircumference, the second wall 21 can expand to lie against the outerwall 24B due tothe bending of the hinge portions 22, 2322,v withoutplacing Astress on ythe, connection between the rst and second Walls. fYet, in normal position, a space between the walls and 2l will bemaintained due to the resilient stiffness of the hinge portions 22, 22which position the second wall 21 inwardly of the first wall Ztl. Thehinge portions extend laterally from the first and second planes of thefirst and second walls 20, 2l, andV can be at right angles thereto butare preferably slightly inclined to extend inwardly toward each other sothat the length of the first wall 2t) between the hinge portions islonger than the second wall. This permits the hinge portions to bendmore easily, and to bend toward a position normal to the walls, when theStrip is rolled into a tube with the second Wall 21 on the inside.

The second wall 2l can be slit-lengthwise, at any suitable place alongthe entire length of the wall portion to create two flaps which may beused either to wrap two bundles of wire, each separately, or to use oneof the flaps to cover the closure inside of thetube. This slitting wouldbe along the dot dash line of FIGURE 3.

Accordingfto the method and apparatus aspects of the present invention,an extruder apparatus 25 is provided. Indicated at v26 is a dischargeend of a heated extrusion cylinder, in which heated plastic material 27ais fed by a screw 28 through a discharge opening 29 into a charnber 30hof a head 3l. Disposed in axial alignment with the propeller 28 in thechamber Stib is a molding structure or extruder portion 25a.

The molding structure l25a is preferably comprised of a series of threeor more interchangeable blocks or forming die portions 26a, 26h, and26C. Closure blocks or plates 26a and 26e comprise end blocks and havelongitudinally Or axially extending Acavities or grooves thereinindicated at 27 and 28 of predetermined configuration for extruding Vtheclosure strips or endsof the strip l@ indicated at 12 and l3`in FIGURE2. l

The central die portion 26h includes a main cavity or pocket areaindicated generally at 29 and in which is mounted a separator wallstructure or plate 3@ which is suspended or hung within the pocket area29 by means of a series of extensions 31 which extensions may comprisescrews 31a extending through the block 26h into the separator 30 forvertical adjustment of the same within the pocket area 29 for varyingthe dimensions of the extruded product. in other words the screws 3iomay be turned up or down to move the plate Sii up or down and therebyeasily simultaneously change the thickness of bot the first and secondwalls 20 and 2l of the tube. This readily controls the Wall thicknessfor serving various purposes. As above described, the first wall 20operates primarily to withstand the lateral stress imposed by theclosure strip edges, and the second wall 2l acts as a second Voroutwardly as the situation may demand).

spaced wall and as a cushioning member protecting the first wall andmaintaining a space therebetween, with forces applied to the second Wallbeing withstood by the second wall, and also by the hinge portions Z2 ateach end. When a special environment is presented which requires eithermore or less strength for lateral forces encountered by the first wall26, or more or less strength for scud resistance or insulatingproperties or similar require- The present invention contemplates oneform of struc-V tnre wherein the walls are of the same thickness. The

invention also contemplates a structure with a first wallV Zti of afirst thickness, and a second wall 21 of a heavier thickness to providebetterinsulative qualities and irnproved scuff resistance wherein eitherthe inside orthe outside of the tube is to be subjected to excessiveseuilC (the tube is then rolled with the wall 21 facing inwardly Theinvention also contemplates a tube wherein the first wall 2t) is of afirst thickness which is larger than the thickness of the second wall2l, such as wherein the material must portion 2li of the strip iti orthe tube Ill being formed within the cavity 32 and the wall portion 21of the strip liti or the tube ll Vbeing formed within the wall cavity33.

Transversely linking the cavities 32 and 33 are trans- -verse linkcavities or grooves indicated generally at 34, 34

wherein linking portions 22,22 of the strip lil or the tube il areformed during the extrusion process. It will be noted that the cavity 33is in alignment with the fastener cavities or grooves Z7 and 23 in theblocks 26a and 26o. In manufacturing a double wall strip one of themajor problems faced was how to keep the walls apart after extrusionuntil they harden. To solve this problem, a fluid system has beendeveloped.

To this end, a series of passageways 35 extend vertically downwardlythrough the block Zeb and through the extensions 3l and then into theseparator wall structure 3l). A second series of passageways V36 extendthrough the separator block 39 which passageways are disposed at rightangles to the passageways 35. A suitable fiuid such as air is forcedthrough the aligned passageways 35 and 36 from the topside of the block2611 through Va supply conduit 37 and the fluid is discharged in adirec- The air passing through the passageways may be cooled such as bya cooler 3S to speed up hardening of the ex- Y truded plastic strip uponits discharge.

Recapitulating the process of rny invention, the mass of heated plasticmaterial is initially moved by the screw 2% into the chamber 3@ therebyproviding a large mass of plastic material which material is being movedaxially against theV molding or extruder portion 25o. The molding`structure 25a operates to divide the mass of heated vthermoplasticmaterial into a series of wall streams and aV series of linking streamsby means of the cavity grooves 3:2, 33 and 34 while contemporaneouslyfurther molding and undulatingl the thermo-plastic material by means ofthe cavities or grooves 27 and 28 in the blocks 26a and 26h to providefastener strips 12 and 13 at opposite ends of the wall portion 21.

As the same is passed through the molding structure 25a the relativelysoft and pliable mass is formed to shape. The coolant which may comprisea cool air stream is directed through the passageways 35 and 36preventing the soft pliable linked wall structure from co1- lapsinguntil the heated thermo-plastic muiti-walled striplike mass is hardenedand is formed into a form sustaining multi-wall strip having fastenerstructure for forming the multi-wall strip into a tubular Wall structure1l.

Through the use of the present method and apparatus the thickness of theweb on which the ribs are mounted may at all times be kept to a minimumsince there is no film 0r sheet to be Welded to them as is the case withsome of the conventional fasteners and a three piece tube may be in thismanner avoided. Reducing the width of the web is of particularimportance on tubes in reducing manufacturing cost, but further sincewhen thin webs are used, the pliability of the tube becomes dependentupon the pliability of the Wall as opposed to the pliability of the webwhere a thick web construction is used.

By utilizing a multi die-block construction, the die blocks can be usedin a great many set ups Without necessitating new die blocks andmanufacturing costs may be thereby kept to a minimum.

It will be understood that modifications and variations may be effectedwithout departing from the scope of the novel concepts of the presentinvention.

I claim as my invention:

1. A mechanism for extruding a multi-wall sheet having fastener elementsat its edges and adapted to be rolled into a tube, the mechanismcomprising means defining an extrusion chamber, a central die memberhaving a die Wall with an elongated die opening therein receivingextrudate from the chamber and provided with upper and lower edgesdeiining outer wall surfaces of the sheet and side edges, edge diemembers beside the central die member having openings dening the outersurfaces of linking portions joined to the sheet formed by the centraldie member for joining the walls of the sheet, a plate member supportedin said die opening of the central die member and constituting a mandrelhaving outer surfaces for defining the inner surfaces of the sheetWalls, means for adjustably supporting said plate member for adjustingits position relative to said opening of the central die member so thatthe thicknesses of said Walls can be simultaneously changed, and meansfor forcing plastic material into said chamber and through the dieopenings.

2. A mechanism for extruding a multi-wall sheet having fastener elementsat its edges and adapted to be rolled into a tube, the mechanismcomprising means defining an extrusion chamber, a central die memberhaving a die wall with an elongated die opening therein receivingextrudate from the chamber and provided with upper and lower edgesdefining outer wall surfaces of the sheet and side edges, edge diemembers beside the central die member having openings defining the outersurfaces of linking portions joined to the sheet formed by the centraldie member for joining the walls of the sheet, a plate member supportedin said die opening of the central die member and constituting a mandrelhaving outer surfaces for defining the inner surfaces of the sheetwalls, means for adjustably supporting said plate member for adjustingits position relative to said opening of the central die member so thatthe thicknesses of said walls can be simultaneously changed, meansdeiining air emission openings in the edge of said plate member fordirecting a iiow of air between the walls of the sheet, means fordelivering air to said openings, and means for forcing plastic materialinto said chamber and through the die openings.

References Cited bythe Examiner UNITED STATES PATENTS 1,476,258 12/23Kroch v13B-55 1,937,069 1l/33 Rado 13S-55 2,583,329 l/52 Eckert 18-55 XR2,720,679 10/ 55 Ratlif 25-17 XR 2,750,631 l/56 Johnson 18-55 XR2,748,401 6/56 Winstead. lS-lZ 3,03 8,205 6/ 62 Plummer 18-55 XR3,103,409 9/63 Bohres et al` 264-209 3,108,851 10/63 Hofer et al.264-209 ROBERT F. WHITE, Primary Examiner.

MORRIS LIEBMAN, ALEXANDER H. BRODMER- KEL, Examiners.

1. A MECHANISM FOR EXTRUDING A MULTI-WALL SHEET HAVING FASTENER ELEMENTS AT ITS EDGES AND ADAPTED TO BE ROLLED INTO A TUBE, THE MECHANISM COMPRISING MEANS DEFINING AN EXTRUSION CHAMBER, A CENTRAL DIE MEMBER HAVING A DIE WALL WITH AN ELONGATED DIE OPENING THEREIN RECEIVING EXTRUDATE FROM THE CHAMBER AND PROVIDE WITH UPPER AND LOWER EDGES DEFINING OUTER WALL SURFACES OF THE SHEET AND SIDE EDGES, EDGE DIE MEMBERS BESIDE THE CENTRAL DIE MEMBER HAVING OPENING DEFINING THE OUTER SURFACES OF LINKING PORTIONS JOINED TO THE SHEET FORMED BY THE CENTRAL DIE MEMBER FOR JOINING THE WALLS OF THE SHEET, A PLATE MEMBER SUPPORTED IN SAID DIE OPENING OF THE CENTRAL DIE MEMBER AND CONSTITUTING A MANDREL HAVING OUTER SURFACES FOR DEFINING THE INNER SURFACES OF THE SHEET WALLS, MEANS FOR ADJUSTABLY SUPPORTING SAID PLATE MEMBER FOR ADJUSTING ITS POSITION RELATIVE TO SAID OPENING OF THE CENTRAL DIE MEMBER SO THAT THE THICKNESS OF SAID WALLS CAN BE SIMULTANEOUSLY CHANGED, AND MEANS FOR FORCING PLASTIC MATERIAL INTO SAID CHAMBER AND THROUGH THE DIE OPENINGS. 